Method of forging components having radially projecting arms, e.g. cruciform components, and to press apparatus for use in carrying out the method

ABSTRACT

In the manufacture of components having at least three radial arms, such as cruciform members for cardan joints, a two-stage operation is carried out instead of a single-stage forging operation. In the first stage a billet is placed in a central region of a die plate from which project a number of columns equal to the number of arms to be formed on the component. The columns are disposed about the billet and project slidingly through a second die plate which is parallel to the first die plate and which is movable towards and away from the first die plate. The billet is pressed between the die plates and is in effect extruded between the columns to form the arms. The member so formed is then placed between two mould elements and forged into the required shape. By reason of the preforming stage, in which no loss of prime metal occurs, the size of the billet necessary to produce the forged component can be substantially less than has been the case heretofore.

United States Patent 1191 Starkier 1451 July 29,1975

[ METHOD OF FORGING COMPONENTS Primary Examiner-C. W. Lanham HAVING RADIALLY PROJECTING ARMS, Assistant Examiner-Robert M. Rogers CRUCIFORM COMPONENTS, A o Attorney, Agent, or Firm-Finnegan, Henderson, PRESS APPARATUS FOR USE IN Parabow and Garrett CARRYING OUT THE METHOD [76] Inventor: Hery Starkier, 21, Rue des Petits [57] ABSTRACT Champs Pans France 75001 In the manufacture of components having at least 22 i 2 1973 three radial arms, 'such as cruciform members for cardan joints, a two-stage operation is carried out in- [21] Appl' bio-14292137 stead of a single-stage forging operation. ln the first stage a billet is placed in a central region of a die plate [30] Foreign Application priority Data frombwhicfh project g1 nfumberj of columns equal to ltne num er 0 arms to e orme ont e component. e Jan. 16, 1973 France 73.01456 columns are disposed about the billet and project SIM 7 ingly through a second die plate which is parallel to [52] U S Cl 72/260 72/374 7 the first die plate and which is movable towards and [51] Int Cl Bzlc 25/08 away from the first die plate. The billet is pressed be- [58] Fieid 256 377 tween the die plates and is in effect extruded between 'g'g the columns to form the arms. The member so formed 5 2 5 i is then placed between two mould elements and forged into the required shape. By reason of the preforming stage, in which no loss of prime metal occurs, [56] References Clted the size of the billet necessary to produce the forged UNITED STATES PATENTS component can be Substantially less than has been the 2,2l6,462 10/1940 Spang 72 412 case h t f 2,869,177 l/l959 Jurgeleit 72/456 5 Claims, 5 Drawing Figures P 5 I Z Z l 9 9 I s s 5 5 IL l 13 j1I 12 Fl "h" "l I r' 1 1 "1111 H 1 l ll l l0 l0 1. I 4 l 1 l 1 1 1 I ll ////J l j\\\\\ A PATENTED JUL29 197s FIG.2

METHOD OF FORGING COMPONENTS HAVING RADIALLY PROJECTING ARMS, E.G. CRUCIFORM COMPONENTS, AND TO PRESS APPARATUS FOR USE IN CARRYING OUT THE METHOD The present invention concerns a method of forging components having radially projecting arms, e.g. cruciform components of the type used for driving shafts, helicopter rotors and the like, and to press apparatus for use in carrying out the method.

The method most frequently used at present in the forging of components having at least three arms com; prisessimply repeatedly applying impacts to a metal billet between two shaping tools until a part of approximately the required shape is obtained. This forging process is not very economical since it involves a loss of prime material amounting to as much as 30 to 40 percent and more, and this is prohibitive when the manufacture of relatively large parts such as helicopter rotors is involved. It will be appreciated that when this procedure is used, the part acquires large flashes or burrs at its corners which have to be trimmed in order to obtain the finished part. The present invention is primarily concerned with improving the method of forging such components.

According to the present invention there is provided a method of forging parts having radially projecting arms, which method comprises, in a first step, squeezing between two substantially planar surfaces, a metal billet disposed within an arrangement of parallel substantially cylindrical columns which are disposed about the billet with their lengthwise axes extending parallel to the direction of the relative movement of the planar surfaces in squeezing the billet, the number of columns corresponding to the number of arms to be provided on the part, and in a second step repeatedly applying impacts to the preformed part thus obtained, while it is positioned between two shaping tools adapted to impart a desired shape to said preformed part.

Thus, during the first forging operation and with the aid of the columns there is obtained a preformed part having the required number of arms of generally rectangular cross-scction, this being achieved without any loss of metal. It will thus be appreciated that this method enables the loss of metal occurring in the manufacture of the components to be considerably reduced. The dimensions of the arms formed during the first forging operation can be made such that when the second part of the forging operation is carried out, the fleshes or burrs formed between the two shaping tools are quite small.

The present invention also provides press apparatus comprising two parallel platens each of which carries a die plate and one of which is movable to move the die plates towards and away from each other, and at least three substantially cylindrical columns secured by one end thereof to one of said platens and arranged with their respective lengthwise axes parallel to each other, which columns are disposed about a central region for containing a workpiece and have their lengthwise axes disposed parallel to the direction of relative movement of the platens, the other of the platens and its die plate having apertures therein through which the other ends of the columns are slidable.

The apparatus is thus very simple and can be fitted equally readily to a hydraulic or mechanical press.

Preferably the die plate on said other platen has liner rings providing apertures through which said other ends of the columns are slidable. This assists in enabling the tools to be renovated in an economical manner when they become worn,

The base of each column may advantageously be slightly tapered to facilitate removal of the preformed part by an ejector disposed in the platen which carries the columns.

Preferably, at least one of said die plates has its surface which faces the other die plate slightly inclined away from the other die plate from the central region towards the periphery, whereby the central region of said surface is nearer than the peripheral parts thereof to the other die plate.

One embodiment of the invention will now be described by way of example with reference to the annexed diagrammatic drawings in which:

FIG. 1 is a simplified sectional view of a press equipped with tools for use in carrying out the method according to the invention,

FIG. 2 is a section on the line llll of FlG. 1,

FIG. 3 is a section on the line lIllll of FIG. 1,

FlG. 4 is a section similar to that of FlG. 3 andshowing the preformed part obtained by the method according to the invention, and

FIG. 5 is a plan view of the finished part.

The press illustrated in FIGS. 1 to 4 has two parallel horizontal platens 1 and 2, one of which is displaceable towards and away from the other. Generally, the bottom plate I is fixed and the upper platen 2, known as the slider, is movable towards and away from the bottom platen by hydraulic or mechanical means not shown in the drawings.

A supporting plate 3 is mounted on the bottom platen l and in it are secured, by means of a second plate 4 constituting a die, vertical cylindrical columns 5 of which there are four in this example. As can be seen more clearly from FIG. 2 or FIG. 3, the parallel columns 5 are disposed at the corners of a square and they are uniformly spaced from each other at a predetermined distance which depends upon the dimensions of the part to be produced.

In the upper platen 2 is mounted a plate 6 formed with cylindrical openings 7 through which the free ends of the columns 5 are adapted to slide during the upward and downward movement of the upper platen 2 of the press. Secured to the plate 6 is a second plate 8 which constitutes the die and in which there are likewise formed openings in register with the openings 7 in the plate 6. It will be seen that these latter openings are lined by cylindrical rings 9 which can be readily removed and replaced simply by disconnecting the die 8 from the plate 6. These rings are preferably made from a highquality steel, whereas the dies 4 and 8 can be made of standard-quality steel.

lt should also be pointed out that the base of each of the cylindrical columns 5 is slightly tapered as indicated at 10 in FIG. 1. This tapering facilitates removal of the shaped part by an ejector 11 provided in the bottom platen I of the press. Also, the operative surface of the die 8 has a slight slope of a few degrees as indicated at 12, for the purpose of facilitating flow of the metal when the workpiece is squeezed.

The first stage of the method of forging cruciform parts or like components with radial burrs comprises squeezing a metal billet 13, preferably in the form of a cube, previously placed in "he central area between the columns 5.

When the upper press platen is lowered towards the bottom platen l, the free ends ,of the four columns 5 first slide in the interchangeable rings 9 in the plate 8, and then in the openings 7 formed in the plate 6, and the metal billet 13 is squeezed between the two dies 4 and 8. As this happens, the metal of the billet flows between each pair of adjacent columns and there is thus finally obtained a part such as that illustrated at l4 in FIG. 4 and having four arms of substantially rectangular cross-section corresponding to the gaps between the columns. It will be seen here that the slight slope of the surface of the die 8 greatly facilitates the flow or sliding of the metal during this forging operation.

After the upper press platen has been completely removed, the preformed part 14 obtained in the manner described above is then ejected from within the arrangement of columns by the ejector 11 provided for this purpose in the bottom platen. This ejection operation is greatly facilitated by the slight taper on each of the columns.

All that now remains to be done is to impart repeated impacts in known manner to the preformed part 14 betweentwo tools of appropriate shape, this constituting the second stage of the method according to the invention and resulting in the production of, for example, a cardan shaft for a motor vehicle such as that illustrated at 15 in FIG. 5. To enable this to be obtained with the minimum loss of metal it is of course necessary that the positions, spacing and diameter of the columns 5 and the reduction in the height of the billet 13 during the pressing operation should be carefully calculated. in particular the generally rectangular cross-section of the arms of the preformed part 14 should be selected to correspond substantially to the volume as determined by the final diameter that is to be obtained. Furthermore, the length of these arms should be slightly less than that of the arms of the finished shaft.

In these conditions and allowing a reasonable safety margin, the flashes or burrs formed between the two tools during the second stage of the process are practically negligibe. It will also be seen that the first stage in the forging of the billet 13 to obtain the preformed part 14 is carried out without any loss of metal. The forging process of the invention therefore finally enables a considerable saving in prime material to be achieved in the manufacture of cruciform parts of this kind as compared with the conventional methods hitherto used.

, Additionally, the fibres of the material of the arms so formed are oriented in the longitudinal direction in contrast to what occurs in the forging methods hitherto used, so that increased strength is imparted to the arms by their very structure.

it will be appreciated that the method can be used just as easily and with the same advantages in the manufacture of Y-shaped parts or parts having more than four arms, simply by altering the number of columns used in the press tool.

I claim:

1. A method of forging parts having radially projecting arms, which method comprises squeezing between two substantially planar surfaces, a metal billet disposed within an arrangement of parallel substantially cylindrical columns which are disposed closely about the billet with their lengthwise axes extending parallel to the direction of the relative movement of the planar surfaces in squeezing a billet, the number of columns corresponding to the number of arms to be provided on the part.

2. Press apparatus comprising two parallel platens each of which carries a die plate and one of which is movable to move the die plates towards and away from each other, and at least three substantially cylindrical columns secured by one end thereof to one of said platens and arranged with their respective lengthwise axes parallel to each other, which columns are disposed about a central region for containing a workpiece and having their lengthwise axes disposed parallel to the direction of relative movement of the platens, the portions of the columns adjacent said central region for containing a workpiece are tapered in a direction towards said other ends, the other of the platens and its die plate having apertures therein through which the other ends of the columns are slidable.

3. Press apparatus as claimed in claim 2, wherein the die plate on said other platen has liner rings providing apertures through which said other ends of the columns are slidable.

4. Press apparatus as claimed in claim 2, wherein an ejector rod is disposed in a bore in the die plate on said one platen for movement to displace a workpiece in a direction towards said other platen.

5. Press apparatus as claimed in claim 2, wherein at least one of said die plates has its surface which faces the other die plate slightly inclined away from the other die plate from the central region towards the periphery, whereby the central region of said surface is nearer than the peripheral parts thereof to the other die plate. 9 

1. A method of forging parts having radially projecting arms, which method comprises squeezing between two substantially planar surfaces, a metal billet disposed within an arrangement of parallel substantially cylindrical columns which are disposed closely about the billet with their lengthwise axes extending parallel to the direction of the relative movement of the planar surfaces in squeezing a billet, the number of columns corresponding to the number of arms to be provided on the part.
 2. Press apparatus comprising two parallel platens each of which carries a die plate and one of which is movable to move the die plates towards and away from each other, and at least three substantially cylindrical columns secured by one end therEof to one of said platens and arranged with their respective lengthwise axes parallel to each other, which columns are disposed about a central region for containing a workpiece and having their lengthwise axes disposed parallel to the direction of relative movement of the platens, the portions of the columns adjacent said central region for containing a workpiece are tapered in a direction towards said other ends, the other of the platens and its die plate having apertures therein through which the other ends of the columns are slidable.
 3. Press apparatus as claimed in claim 2, wherein the die plate on said other platen has liner rings providing apertures through which said other ends of the columns are slidable.
 4. Press apparatus as claimed in claim 2, wherein an ejector rod is disposed in a bore in the die plate on said one platen for movement to displace a workpiece in a direction towards said other platen.
 5. Press apparatus as claimed in claim 2, wherein at least one of said die plates has its surface which faces the other die plate slightly inclined away from the other die plate from the central region towards the periphery, whereby the central region of said surface is nearer than the peripheral parts thereof to the other die plate. 